+1 on Kirkn's comments Pete, don't use that helmet for anything more than a flower pot. The styrofoam liner between the fibreglass shell and the soft foam cushion has a life of around 5 years, and after that, it sets like concrete and provides no "shock absorbtion" if you get spat down the road and your head smacks the pavement.
Just like you wouldn't ride on 30 year old tires, no matter how good they look, you'd be stupid to ride with a 30 year old helmet, no matter how cool it looks. Cheers, Terry.